While I am very familiar with black & tan APBTs, it's also true that the same color pattern is shared among several different breeds. Whatever the case, I don't believe that the dog on Petfinder is purebred anything.

And that dog from the apbtconformation page is plain hideous. It is overdone & does not resemble the working APBT. I would call it an AST at best.

To be fair, the shelter may know something that you don't. At our shelter we had a mom with 10 babies. She was a AKC boxer. She had also been around the neighborhood and must have had several fathers for her babies. She had one puppy that looked like a husky mix, one that looked like a blond lab and one that looked exactly like a purebread chow as well as all mixes between. Not one of them looked anthing like a boxer. You should have seen the looks on people faces when we were trying to convince them that yes, these babies were boxer mixes. Esp since mom was gone at that point.
This dog obviously has pit and should have that listed somewhere, but it is not beyond possiblity that yes, there is some hound in there too.